We are facing a problem in crude/condensate decanting which is received from local fields. Settling time for the oil tankers is one hour; after this a dip is taken, water observed in the dip is nil. Then we decant the tankers into our crude oil tanks. After settling time for the tanks we are observing raised water level. What can be the potential causes?
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29/10/2020
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Joel Kaye, Retired from UOP & Tesoro, kaye13@gmail.com
Another casue, if your tanks have sediment on the bottom, water will collect in pockets, and your dip may not be representative of the tank contents.
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24/07/2020
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Manoj, Lummus Global Pte. Singapore, parasharmk@yahoo.com
The settling time is dependent on the stability of the emulsion. Surface active compounds like some well additives, corrosion inhibitors , H2S scavengers can stabilise the HC / water emulsion so may take some hours or even days to settle out.
We often see the Interfacial tension between water and condensate can be around 6-10 dynes/can range so settling can take considerable time or maybe not readily settle at all. A high efficiency LL coalescer can break such an emulsion and prevent water dropout in tanks and corrosion of tanks.
Another possibility is the temperature difference between arriving crude/condensate tankers and ambient temperatures in the tank. Water solubility is temperature dependent so cooling in tanks can see dissolved water condense into free water.
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20/07/2020
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keith bowers, B and B Consulting, kebowers47@gmail.com
Tankers are not settling long enough and level enough. You must sample through the bottom valve to ensure water is caught. 'Water finding paste' on a measuring tape bob is better than 'dipping'. Obviously water is not being adequately detected from the tankers.
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20/07/2020
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Sounds like your one hour initial settling time is not enough to remove the water, so it doesn't drop out until it hits the larger tanks with presumably more residence time. If the decanter was settling water in the past, then something has changed. Higher rate, higher density/viscosity on the condensate, increased solids or other contaminants, or changes in chemical additives being added at the production site could all possibly contribute to any changed performance.
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20/07/2020
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Nagarathinam S Murthy, Ashphil Consultancy, Chennai, nssvdvr@gmail.com
Use Stoke's law to check the terminal velocity and in turn required time of settling. One could get a reasonable period for effective separation of water.
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20/07/2020
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Prakash Pimparkar, Environmental Consulting Services , prakash.pimparkar@yahoo.in
Separation of water from oil is a function of time.Crude tanks are huge with storage time of a few weeks giving ample time for separation. So as there may not be separation in tankers in one hour, but good separation in storage tanks. This is very normal and provisions are made for periodic removal of accumulated water.
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20/07/2020
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Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
The settling time is dependent on the stability of the emulsion. Surface active compounds like some well additives, corrosion inhibitors , H2S scavengers can stabilise the HC / water emulsion so may take some hours or even days to settle out.
We often see the Interfacial tension between water and condensate can be around 6-10 dynes/ can range so settling can take considerable time or maybe not readily settle at all. High efficiency LL coalescer can break such an emulsion and prevent water drop out in tanks and corrosion of tank.
Another possibility is temperature difference between arriving crude/ condensate tankers and ambient temperature in tank. Water solubility is temperature dependent so cooling in tanks can see dissolved water condense into free water.
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